Questions On RCR123 & 16340. What's The Difference?

What’s the difference between a 3.7V RCR123 and a 3.7V 16340 rechargeable lithium cell? Aren’t they the same size and voltage? Thanks in advance!

Difference afaik is the name. Same cells, different names. RCR is the rechargeable version of the common CR123. Most people don’t know the 16340, 14500, 10440, 18650s of the world